Space debris: Seismometers can track a crash almost in real-time
When large satellites crash to Earth, we have so far been largely blind to their trajectory. This could change thanks to technology from earthquake research.
The crash of Shenzou 15 could also be observed with the naked eye
If space debris does not completely burn up in the atmosphere during a crash to Earth, seismometers installed for earthquake research could help to find crash sites much faster in the future than has been possible so far. This is the opinion of two researchers from the USA and Great Britain, who demonstrated this using the example of the uncontrolled crash of a module of a Chinese space station. Seismometers in Southern California were able to track the trajectory of the crashing capsule, named Shenzhou-15, almost in real-time based on the sonic boom. The 1.5-ton object also potentially posed a danger to people on the ground in early April.
So far, we are blind to such crashes
As seismologist Benjamin Fernando of Johns Hopkins University and his colleague Constantinos Charalambous explain, their method utilizes the high speed of space debris as it hurtles through the Earth's atmosphere. Because they are traveling at supersonic speeds, they produce shock waves that cause the Earth's surface to vibrate and can therefore be measured by seismometers. By combining the data from multiple measuring instruments, the trajectory of the burning debris through the Earth's atmosphere can be tracked live. While this is not enough to warn of the impact site in time, at least potentially dangerous debris can be found and recovered much more quickly.
(Image:Â Benjamin Fernando / Johns Hopkins University)
Even though efforts are underway worldwide to reduce the amount of space debris in orbit and prevent uncontrolled crashes, they still occur. Older technology, in particular, can pose a danger even if no one on the ground is hit, the two researchers recall. For example, in 1996, a failed Russian Mars probe crashed without its remains being found afterward. Only years later, artificial plutonium, believed to be from the mission and contaminating the area, was discovered in a glacier in Chile. If the trajectory of the crashing probe could have been tracked more precisely, it would not have taken so long, the two researchers suggest.
Videos by heise
Currently, the trajectory of falling objects is primarily predicted using radar measurements, but this is not very accurate. Seismometers can help to make the trajectory visible up to shortly before impact in the future. This is also important against the backdrop of the increasing number of falling objects. Last year, one to two satellites crashed every day, and the number will only continue to grow. The satellite internet Starlink is primarily responsible for this so far, but other mega-constellations of thousands of satellites will cause the numbers to rise sharply again. Even if these satellites burn up upon re-entry, such tracking could be enormously helpful. The researchers present their work in the scientific journal Science.
(mho)
